Wheeled personal transportation device

ABSTRACT

A motorized device for transporting a human or inanimate payload. A platform is configured to accommodate the payload and a pair of wheel clusters are mounted to the platform at opposite ends thereof and are powered in both rotation and in translation relative to the platform, for example by one or more electric motors housed in or on the platform or wheel clusters. Each of the wheel clusters comprises an arm, and a first and a second wheel rotatably mounted to respective opposite ends of the arm. Each of the wheels is independently powered about its respective axis of rotation. An electronic controller commands the motors to enable stable rolling movement of the device over a surface with only one wheel of each cluster in contact with the surface, and to allow the device to steer and to ascend and descend steps.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) to GB Application 1618983.9 filed Nov. 10, 2016, which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

One of the major drawbacks to most, if not all, forms of publictransport is the integration of transport solutions into users' dailylives. It is common for the first and/or final miles of a journey totake a disproportionate amount of time and effort in the context of theoverall journey. This is one of the most common reasons given for theuse of private transport: that it can provide a truly door to doorsolution. As a result, there is a clear need for convenient, efficientfirst/final mile transportation.

BACKGROUND

There are several disparate technologies that provide a partial solutionto this problem. Self-balancing single axle devices, such as electricunicycles, Segway® and hover-boards can provide transportation oversubstantially flat terrain and have a reasonable range, but they areeasily stopped by steps, curbs and other street furniture. Furthermore,they are too heavy and bulky for easy stowage and therefore they do notintegrate well with other transport solutions as they occupy too muchspace within a vehicle, if, indeed, they can even be successfully stowedwithin the vehicle.

There are also two axle systems, which have the potential to be morestable than single axle systems. However, they also fail to address theissue of changes in height at curbs, steps and gaps.

Stair-walkers and other similar three-wheel cluster devices have beendeveloped specifically to deal with stairs. However, they are typicallytoo heavy and bulky for stowage within a vehicle or integration withother transportation solutions.

It is against this background that the present invention has arisen.

SUMMARY

According to a disclosed embodiment of the invention, a device fortransporting a payload over a varied terrain is provided. The devicecomprises a planar platform configured to accommodate the payload and apair of wheel clusters mounted to the platform at opposite ends thereof.The wheel clusters are powered in both rotation and in translationrelative to the platform. Conversely, depending on the assumedframe-of-reference, the platform is powered in both rotation and intranslation relative to the wheel clusters. Each of the wheel clusterscomprises an arm, and a first and a second wheel rotatably mounted torespective opposite ends of the arm. Each of the wheels is independentlypowered about its respective axis of rotation.

A plurality of motors is provided to power the rotation and translationof the wheel clusters relative to the platform, and also the rotation ofthe wheels relative to the arms. The motors may be electric motorshoused in or on the platform or wheel clusters. The device furthercomprises an electronic controller commanding the plurality of motors toenable stable rolling movement of the device over a surface with onlyone wheel of each cluster in contact with the surface. The independentcontrollability of each wheel and of the wheel clusters relative to theplatform allows the device to steer and to negotiate (ascend anddescend) steps.

Regarding the translation of the platform is relative to the wheelclusters, the platform may be positioned anywhere along a continuumdefined between a first position substantially aligned with a firstwheel in each of the first and second wheel cluster and a secondposition substantially aligned with a second wheel in each of the firstand second wheel cluster.

Within the context of this invention the term “payload” is used to referto any load to be transported and is intended to include, but not belimited to: the user, another person, one or more animals, an inanimatecargo which could include airport luggage, grocery shopping or anycombination of the aforementioned.

Within the context of this invention, the term “varied terrain” is usedto refer to every type of pedestrian infrastructure in a range oflocations. It is intended to include city street fixtures includingcurbs, sidewalks, pavements, individual steps up or down, multiple stepsup or down, gaps such as those found between the train and the platformedge or any combination of the aforementioned. It is also intended toinclude tarmac, flagged, gravel, tiled or carpeted surfaces and othersimilar terrain.

According to a further feature of the disclosed embodiment, the devicemay comprise at least one sensor detecting an approaching step andproviding an input to the controller.

According to a further feature of the disclosed embodiment, the devicemay comprise at least one sensor operative to detect a leaning motion ofa user standing on the platform and provide an input corresponding tothe leaning motion to the controller.

The arms of the wheel clusters may be oriented substantially verticallywhile the platform remains substantially horizontal. The platform maythen translate relative to the arms, moving upward (in the verticalplane), and this combined with the rotation of the platform with respectto the arms enables smooth transitions across gaps and up/down curbs,thereby achieving integration with all aspects of pedestrianinfrastructure.

The ability of the platform to be located at any point on the continuumbetween the two listed extremes enables the platform to be located halfway between the extremes in order to provide a stable, four-wheeled loadcarrying configuration.

The plane of the first wheel cluster is substantially parallel to theplane of the second wheel cluster. The plane of the platform issubstantially orthogonal to the planes of the first and second wheelclusters.

The distance between the centers of the two wheels in each cluster maybe greater than the sum of the radii of the two wheels. If this were notthe case, then the wheels would overlap and interfere with one another.

The distance between the two wheels centers in each cluster may begreater than the height of a curb that the device is expected to climb.This ensures that the center of the top wheel can rise above the curband facilitate the transfer of weight onto the curb.

The device may further comprise one or more motors configured to powerthe translating mechanism of the platform relative to the wheels. Thedevice may further comprise one or more additional motors configured topower the rotation of the wheel clusters relative to the platform. Thedevice may further comprise a motor provided in the hub of each wheel.This enables the wheels to be independently driven.

In some embodiments, the provision of a motor configured to power therotation of the wheel clusters relative to the platform enables centerof gravity (CoG) balancing on substantially flat even ground. In thisscenario, the default orientation of the platform is substantiallyhorizontal. Balancing occurs by minute variations of speed of drivenwheels. If the payload were to lose balance forwards then the devicebelow the payload accelerates to re-center the payload center of gravitybetween the two axles linking wheels in contact with the ground at thatpoint.

The device may further comprise at least one sensor operative to detectupward and/or downward steps which the device is approaching. The sensormay advantageously be an ultrasound device or an optical sensor(camera).

All four wheels, i.e. both wheels in each of the two-wheel clusters maybe configured to contact the ground simultaneously to enable loading ofthe payload. With all four wheels simultaneously in contact with theground, the device is stable. This enables the user to stand in a stablecondition on the device, prior to commencing transportation.

The device may further comprise a control system. The control system mayinclude a user interface to enable the user to register the requirementto step up or down. The control system is further configured to controlthe motors in response to data from the sensors in order to achievesmooth transportation of the payload.

When the user mounts the device, or an inanimate payload is loaded on tothe device, the device is preferably configured in its most stableconfiguration, namely with all four wheels in contact with the ground.This de-skills the mounting of the device for the user and provides astable platform for an inanimate payload. In order to commencetransportation, the control system then drives the platform towardseither the front or the rear wheel cluster. Once the rotation axle ofthe platform is perfectly coincident and coaxial with the axis projectedthrough the wheel from each cluster to which it was driven, then theplatform rotation motor rotates the wheel clusters by 90 degrees andthereby lifts one wheel in each wheel cluster in a rotating motion untilthey are above the other wheel in each cluster.

The invention will now be further and more particularly described, byway of example only, and with reference to the accompanying drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a two-wheel cluster configuration of the device with theplatform in the lower position for normal driving on substantially flatground;

FIG. 2 shows the two-wheel cluster configuration of the deviceconfigured to carry an inanimate payload on a substantially flatsurface;

FIG. 3A to 3C show the two-wheel cluster configuration climbing anddescending steps;

FIGS. 4A to 4G show various steps in the sequence of the two-wheelcluster configuration climbing steps;

FIGS. 5A to 5D show various steps in the sequence of the two-wheelcluster configuration descending steps;

FIG. 6 shows a three-wheel cluster configuration;

FIGS. 7A to 7E show details of wheel configurations for a three-wheelcluster configuration;

FIGS. 8A to 8F shows examples of the connection between the three-wheelcluster and the platform;

FIG. 9 is a schematic showing the constituent parts of a control system;

FIG. 10 is a flow diagram showing one example of the steps associatedwith setting up the device;

FIGS. 11A to 11C show the device of FIG. 6 climbing a step;

FIGS. 12A to 12C show various modes of operation of the device of FIG.6;

FIG. 13 shows the device of FIG. 6 descending a flight of stairs; and

FIGS. 14A and 14B show the stowage of the device in a vehicle.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

FIG. 1 shows a two-wheel cluster configuration of a device 10. Thedevice 10 comprises a first cluster comprising two wheels 20A, 20Bmounted to a first link arm 12 (visible in FIG. 1) and a second clustercomprising two wheels 20A, 20B mounted to a second link arm 12. FIGS.1-5 depict only the two-wheel cluster attached to the end of theplatform 30 nearest to the viewer, and it is to be understood that asecond two-wheel cluster is generally identical to that shown and isattached to the opposite/far end of the platform 30, to create afour-wheeled device 10. Each wheel 20A, 20B is provided with an electricmotor which powers the wheel in rotation relative to the link arm 12, asdescribed in greater detail hereinbelow.

The device 10 also comprises a platform 30 on which a payload is carriedduring use. The platform 30 has a generally flat upper surface whichdefines a payload-carrying plane which is maintained in a generallyhorizontal orientation during use of the device 10. The platform 30 isprovided with a rotation mechanism 302 and force break-away ratchet 304to permit angular displacement between the link arm 12 and the platform30 caused by sudden high torque. The link arm 12 is further providedwith a belt-driven translating arrangement to enable the movement of theplatform 30 along the length of the link arm 12.

FIG. 1 shows the device 10 is the normal driving condition onsubstantially flat ground with an animate payload, typically a person,with the platform 30 aligned with the lower wheels 20A. Thisconfiguration provides greater stability and feeling of safety for theuser.

It is also possible for the device 10 to be configured such that thenormal driving condition is inverted so that the platform 30 is alignedwith the upper set of wheels 20, as shown in FIG. 4B. This configurationenables the device 10 to step up (see FIGS. 4C-4F) without preparation,but it may require the user to be more confident and the balancingsystem to be configured to react in shorter time intervals and withhigher power. These adaptations are required because the out of balanceforces will be much greater if the normal driving position is highbecause the platform on which the load rests has a long lever which willincrease the moment about the contact patch on the wheel on the groundby the ratio (L+r)/r.

FIG. 2 shows a two-wheeled configuration of the device 10 configured tocarry a payload over a substantially flat surface. The payload may beinanimate, although this configuration can also be used for a humanpassenger depending on the driver's usage choice. This configuration maybe appropriate for a human payload if stability is a priority ratherthan speed or distance. The platform 30 is positioned at the mid-pointof the link arm 12 and rotated to be substantially parallel with thelink arm 12 so that all four of the wheels 20 are in contact with theground. An inanimate payload 66 is positioned on the device 10.

FIGS. 3A to 3C show the two-wheeled configuration of the device 10carrying loads up and down stairs. This action is aided by a lever 50,shown in FIG. 3A. The lever 50 enables the device 10 to operate in asemi-autonomous mode so that the user can guide the device 10 withouthaving to bear the weight of the payload 66 at any time.

FIG. 3B shows the device travelling from right-to-left and downward todescend a step or a set of stairs. The platform 30 has translated alongthe link arm 12 (to the left as viewed in FIG. 3B) towards theleading/lower wheel 20A, and the trailing/upper wheel 20B is thenrotated counterclockwise about the axis of wheel 20A to contact thelower step and become the new leading/lower wheel. The platform 30 thencontinues to translate in a leftwards and downwards direction, this timetraveling the other way along the link arm 12, towards wheel 20B again(which is now the leading wheel). By repeating this sequence, the device10 moves down the steps.

FIG. 3C shows the device 10 travelling from left-to-right and upward toascend a step or a set of stairs. The platform 30 has translated alongthe link arm 12 (to the right as viewed in FIG. 3C) towards theleading/upper wheel 20A, and the trailing/lower wheel 20B is thenrotated clockwise about the axis of wheel 20A to contact the upper stepand become the new leading/upper wheel. The platform 30 then continuesto translate in a rightward and upward direction along the link arm 12,towards wheel 20B again (which is now the leading wheel). By repeatingthis sequence, the device 10 moves up the steps.

FIGS. 4A to 4G show the various stages of the step climbing operationfor the two-wheel cluster device 10. In some embodiments, theillustrated steps are initiated solely in response to a sensor mountedto the device 10 (as described further hereinbelow) identifying therequirement for the device to step up. In some embodiments, a userinterface may be provided such that the user can initiate a stepclimbing procedure.

The device 10 is configured to undertake normal driving with theplatform 30 low, preferably in line with the lower set of wheels 20A asillustrated in FIG. 4A. When the device detects that it is approaching astep up, the platform 30 is elevated into line with the upper wheels20B. FIG. 4B shows the user driving the device 10 forward towards thestep up. The platform 30 is tilted from the horizontal position so thatthe leading edge of the platform is below the trailing edge. Thisresults in the lower wheels being powered forward by the motors providedwithin the hubs.

In some embodiments, the platform may be provided with two pressurepads. These are configured to enable the device to steer left and right.The user will apply an increased pressure to one of the two pads inpreference to the other in order to guide the device around a corner.This pressure differential will be communicated from the pressure padson the platform, through the control system and the turning of thedevice will be realized by increasing the torque provided by the hubmotor in the wheels on the outside of the corner. For example, if theuser applies an increased pressure on the left pressure pad, then thewheels from the right wheel cluster that are in contact with the groundwill accelerate to drive the device around the corner.

In some embodiments, the platform may be split into two sections thatare articulated such that the differential pressure provided by a usersignaling an intent to turn a corner results in a physical depression ofone of the sections of the platform relative to the other. This heightdifference, of either the entire side of the platform, or the leadingedge thereof, will be interpreted by the control system as requiring adifferential torque between the wheels in order to drive the devicearound the corner.

As shown in FIG. 4C, the user leans back to control the device 10 toslow down as the device 10 approaches the curb or other step up.Although this illustration shows the device 10 climbing a single step,it will be apparent that the sequence would be equally applicable to aseries of steps. As the lower wheel 20A of the device 10 hits the riserof the step, the lower wheel stops instantaneously. The kinetic energyof the device and payload provides forward momentum which in turncreates rotation about the axle of the lower wheel 20A. Because usercontrol is slowing the device down, there is reverse torque on the lowerwheel 20A. When this wheel is stopped by the curb, and power is notinstantly cut to the wheel, then the reverse torque rotates the link arm12 and platform 30 forwards aiding the progress of the upper wheels 20Band payload to continue in the forward direction.

The force on the link arm 12 creates a torque against the platform 30which is held substantially level by the user's mass and balance onhis/her feet, causing a break-away feature or controlled release ofangular connection between link arm 12 and the platform 30. As shown inFIG. 4D, the user's momentum and mass now effectively let him rotateforwards (clockwise about the axis of the trailing/lower wheel) alongwith the platform 30.

As soon as the upper wheel 20B hits the raised surface as shown in FIG.4E, the moment of the platform 30 is arrested and the remaining momentumof the user causes him to lean forwards on the platform 30, providingcontrol input for forward propulsion to both wheels 20A, 20B in eachcluster, i.e. to all four of the wheels that are powered at the pointillustrated in FIG. 4E. All of the weight of the payload is on the frontwheel 20B, the link arm 12 is still disconnected from the platform andthe device 10 drives on, dragging the (also powered) lower wheel 20A upthe curb. At this point, the device 10 is balancing on only the frontwheels 20B as if the rear wheels 20A did not exist as the link arm 12 isstill free to rotate relative to the platform 30.

As soon as the control system detects the following wheel 20A is on thesame surface as the front wheel 20B as illustrated in FIG. 4F, thecontrol system instructs the link arms 12 to be powered forwards in aclockwise manner relative to the platform 30. The unloaded wheels 20Amove up until the link arm 12 is generally perpendicular to the platform30 again as shown in FIG. 4G. Once the position illustrated in FIG. 4Gis reached, the platform 30 and link arm 12 lock their rotational jointagain. The step climbing sequence is completed for the configuration inwhich the normal running position is with the platform 30 in line withthe lower wheels (now 20B).

In some embodiments, where there is no ratchet or clutch disconnect, therotational joint will not be locked again because the rotation of thelink arm 12 relative to the platform 30 is controlled by drive and forcesensors. In such an embodiment, the motor controlling the rotation ofthe platform relative to the link arm 12 arrests the rotation when theplatform is in one of four predetermined preferred drive configurations,which are defined to be 0°, 90°, 180° and 270° where, 0° and 180° arethe horizontal four-wheel drive modes (depicted in FIG. 2).

If the desired or default running position is with the platform 30 inline with the upper wheels, the belt drive translates the platform 30back up to the upper wheel center as illustrated in FIG. 4B.

FIGS. 5A to 5D illustrate the various stages in the descent of a step bythe two-wheel cluster configuration. The kinematics for approaching astep down are inversed relative to the step-up procedure described abovewith reference to FIGS. 4A to 4G.

In some embodiments, the illustrated sequence may be initiated solely inresponse to a sensor 42 identifying the requirement for the device tostep down (or up). In some embodiments, a user interface may be providedto allow the user to initiate the step climbing or descending sequence.

If the riding position is high (as in FIG. 4B) when approaching theobstacle, then before reaching the curb or step down the platform 30 islowered to the axle of the lower wheel 20A so that the device isconfigured as illustrated in FIG. 5A. If the riding position is low,then FIG. 5A illustrates the normal driving position and the stepdescending operation is commenced by the rotation of the link arm 12with the free raised wheels 20B forwards till they contact the ground torun ahead of the loaded lower wheels 20A, which are now in a rearwardposition relative to the unloaded wheels 20B. This condition isillustrated in FIG. 5B. The control system detects that the front wheels20B are now in contact with the floor, but continues to provide downwardforce on the link arm 12 pushing the front wheel 20B against the floor.

As soon as the system detects that the front wheel 20B has contacted thelower level as illustrated in FIG. 5C, the controller briefly brakes allwheels 20A, 20B to retard the forward motion of the device 10. Thedetection that the front wheel 20B has contacted the lower level may beachieved by detecting that the rotation of the link arm 12 has ceased orby an accelerometer placed at each extreme of the link arm, which willdetect when the downward motion of the forwards extreme of the link isabruptly stopped. The braking force on the front/lower wheel 20B createsan opposite rotational force on the link arm 12, moving the platform 30forwards and upwards. This motion is matched by the forwards momentum ofthe user, with the platform pressing upwards against the user, liftingthem upwards. This motion is indicated by the arcing arrow in FIG. 5D.The free motion of the user, applied against the braked motion of thedevice 10 results in the user leaning forwards on the device 10 and thecontroller releasing the brakes on the lower wheel 20B to startre-balancing the user on the device 10.

If the device is configured for normal running with the platform 30 inline with the lower pair of wheels (now 20B), then once the user isrebalanced on the platform 30, the belt drive will power the platform 30down the link arm 12 until it is level with the lower pair of wheels20B.

In the embodiment of FIGS. 1-5, it may be seen that the movement of theplatform in the vertical plane combined with the rotation of theplatform with respect to the wheel clusters enables smooth transitionsacross gaps and up/down curbs, thereby achieving integration with allaspects of pedestrian infrastructure.

Also in the above embodiment, the ability of the platform to be locatedat any point on the continuum between the two listed extremes enablesthe platform to be located half way between the extremes in order toprovide a stable, four-wheeled load carrying configuration.

Also in the above embodiment, the plane of the first wheel cluster issubstantially parallel to the plane of the second wheel cluster. Theplane of the platform is substantially orthogonal to the planes of thefirst and second wheel clusters. The distance between the centers of thetwo wheels in each cluster may be greater than the sum of the radii ofthe two wheels. If this were not the case, then the wheels would overlapand interfere with one another. The distance between the two wheelscenters in each cluster may be greater than the height of a curb thatthe device is expected to climb. This ensures that the center of the topwheel can rise above the curb and facilitate the transfer of weight ontothe curb.

The FIG. 1-5 device may comprise one or more motors configured to powerthe translating mechanism of the platform relative to the wheels. Thedevice may further comprise one or more additional motors configured topower the rotation of the wheel clusters relative to the platform. Thedevice may further comprise a motor provided in the hub of each wheel.This enables the wheels to be independently driven.

In some embodiments of the above device, the provision of a motorconfigured to power the rotation of the wheel clusters relative to theplatform enables center of gravity (CoG) balancing on substantially flateven ground. In this scenario, the default orientation of the platformis substantially horizontal. Balancing occurs by minute variations ofspeed of driven wheels. If the payload were to lose balance forwardsthen the device below the payload accelerates to re-center the payloadCoG between the two axles linking wheels in contact with the ground atthat point.

As discussed above, the device may comprise a sensor to detect upwardsteps. This detection would be required in the circumstances where thedevice is configured to ride with the platform low and then toanticipate an upward step by raising the platform. This configurationhas the advantage of increased stability, control and feeling of safetyfor the rider. The device may further comprise a sensor to detectdownward steps. The sensor may be an ultrasound device or a camera.

All four wheels, i.e. both wheels in each of the two-wheel clusters, maybe configured to contact the ground simultaneously to enable loading ofthe payload. With all four wheels simultaneously in contact with theground, the device is stable. This enables the user to stand in a stablecondition on the device, prior to commencing transportation.

As discussed above, the device may comprise a control system. Thecontrol system may include a user interface to enable the user toregister the requirement to step up or down. The control system isfurther configured to control the motors in response to data from thesensors in order to achieve smooth transportation of the payload.

When the user mounts the device, or an inanimate payload is loaded on tothe device, the device is preferably configured in its most stableconfiguration, namely with all four wheels in contact with the ground.This de-skills the mounting of the device for the user and provides astable platform for an inanimate payload. In order to commencetransportation, the control system then drives the platform towardseither the front or the rear wheel cluster. Once the rotation axle ofthe platform is perfectly coincident and coaxial with the axis projectedthrough the wheel from each cluster to which it was driven, then theplatform rotation motor rotates the wheel clusters by 90 degrees andthereby lifts one wheel in each wheel cluster in a rotating motion untilthey are above the other wheel in each cluster.

FIG. 6 shows an embodiment of device 10 having a three-wheel clusterconfiguration. There are six drive wheels 20 formed in two clusters,each cluster having three wheels. Each wheel has a hub 21, a pluralityof spokes 23 and a tire 25. The number of spokes is selected to balancethe requirement for strength with the requirement that the device issufficiently light to be handled with ease. The tire 25 may befabricated from rubber or plastic and is preferably provided with atread pattern to ensure that the tires 25 do not slip on wet surfaces.The tire may also be pneumatic and may therefore also include an innertube (not shown).

The upper surface of the platform 30 may have a non-slip surface 32. Theplatform 30 may also be provided with lights 34 which ensure that thedevice is visible to other users of the pavement, sidewalk, trainstation or wherever else the device is deployed, but additionally, thelights 34 enable a user riding the device 10 in the hours of darkness tosee clearly what is directly ahead of the device 10.

Each of the six wheels 20 is provided with a drive wheel motor 22located in hub 21. All six of these motors 22 are independentlycontrolled. This ensures that power is only provided to those wheels 20in contact with the ground at any one time. This provides a steeringcapability by feeding more power to the wheels at one side of the devicethan to those at the other side of the device, thereby causing thedevice to turn.

Each cluster is provided with a wheel carrier 24 which is configured tointerconnect the three wheels of each cluster. The wheel carrier 24 mayadvantageously be an equilateral triangle. The wheel carrier 24 holdsthe three wheels of the cluster in fixed relative position. The wheelcarrier 24 also provides conduit for communication with and supply ofpower to the wheels 20. The wheel carrier 24 effectively defines threewheel axes A₁, A₂, A₃ between adjacent wheels, as illustrated in FIGS. 6and 7A. The three wheels 20 in each cluster are preferably equidistantfrom one another. The cluster rotation axis is at the intersection I ofthe three perpendicular lines bisecting each of the connecting linesbetween pairs of adjacent wheel centers.

The relationship between the size of the wheel carrier 24 and the radiusof the wheels 20 is set out in FIGS. 7B through 7E. Although each ofthese figures shows two wheels only, it will be understood that thesecould be two wheels that form part of a three-wheel cluster. In thethree-wheel embodiment, the third wheel would be located at the positionindicated in phantom lines at 20′ in FIG. 7B. The third wheel is omittedentirely from FIGS. 7C-7E for clarity of illustration.

FIG. 7B illustrates the relationship between the wheel radius r, theaxle pitch L, the wheel gap D and the width, S, of the platform 30.These factors, together with the height of the curb, H, all contributeto the optimization of the configuration of the device. Curbs typicallyhave a height of 200 mm of less. Therefore, in some embodiments, thefollowing proportions are deployed:

150 mm>r>H/1.75

L>2r

S<r/2

20 mm<D<S

In some embodiments r may be between 115 mm and 150 mm; L may exceed 230mm; S may be within the range 50 mm to 75 mm; and D may be within therange 20 mm to 75 mm.

FIG. 7C illustrates in further detail the design constraint that L mustexceed H. The center of the leading/upper wheel must land on the top ofthe curb as illustrated in FIG. 7C, otherwise the device may fail toclimb the curb and may slip down again. In order to ensure effectivelycurb climbing L, which is the sum of the wheel diameter 2R and the wheelgap D, must exceed the height H of the curb.

FIGS. 7D and 7E illustrate two extreme configurations that would not beeffective. As illustrated in FIG. 7D, the radius r of the wheels is toosmall and therefore the platform contacts the curb edge, preventing asmooth curb climbing operation. As illustrated in FIG. 7E, the axlepitch L is only equal to the wheel diameter 2r, which is also equal tothe curb height H. The upper wheel therefore cannot effectively land onthe curb and the device cannot climb the curb. Furthermore, the wheelswithin each cluster will interfere with one another because L does notexceed 2r and therefore a device thus configured would not be operable.

The device 10 may comprise a control and sensing system operative torotate forward and place the redundant wheels (those not initially incontact with the ground surface) in front of the obstacle whendescending a step. The sensing system may further comprise anacceleration sensor or accelerometer. This would be configured such thatwhen the device comes into contact with a curb it records a high ‘g’deceleration, for example when the device is climbing a step. Thesensing system will further comprise a controller programmed to initiatea curb-climbing sequence when the acceleration sensor registers a valueof accelerating exceeding a predetermined value. The predetermined valuemay be 0.2 g or 2 m/s².

The sensing system may be further configured to sense when the redundantwheel hits the ground, signaling a return to even ground driveparameters.

As seen in the embodiment disclosed in FIGS. 6 and 7, the plane of thefirst wheel cluster may be substantially parallel to the plane of thesecond wheel cluster. The plane of the platform may be substantiallyorthogonal to the planes of the first and second wheel clusters.

As described in relation to the embodiment disclosed in FIGS. 6 and 7,each wheel may be independently driven and this independent drive may beachieved through a motor provided in the wheel hub. This ensures thatthe wheel from each cluster that is not in contact with the ground doesnot rotate aimlessly. It also allows differential wheel speeds enablingeffective cornering and climbing.

As described in relation to the embodiment disclosed in FIGS. 6 and 7,the platform may be controlled in a manner to ensure that it remainssubstantially level/horizontal when negotiating (climbing and/ordescending) one or more steps. This is enabled by the independentlydriven aspect of the platform as described above. The wheels clustersmay be commanded to create angular rotation of the wheel clusters withrespect to the orientation of the platform.

As described in relation to the embodiment disclosed in FIGS. 6 and 7,the first and second wheel clusters may be configured and controlled sothat there are four wheels in contact with the ground during normalrunning. In this context, the term normal running is used to denote themajority of activity covering substantially even ground. It includes anyactivity which is not a height transition or curb climbing maneuver.

As described in relation to the embodiment disclosed in FIGS. 6 and 7,the platform may be capable of rotation relative to the axle joining thefirst and second three-wheel clusters in order to achieve the stepclimbing capability of the device. Because the platform can rotaterelative to the axle joining the three-wheel clusters, when the forwardmost wheel of each cluster hits an upward step or curb, the kineticenergy of the payload initiates a rotation about the front wheel axis.

As described in relation to the embodiment disclosed in FIGS. 6 and 7,the rotation of the platform relative to the axis joining the first andsecond three-wheel clusters may be powered. The provision of a platformcapable of powered rotation relative to the axle joining the first andsecond wheel clusters enables many of the key aspects of the design tobe realized. In some embodiments, the device may be configured such thatthere is a default orientation for the platform that is parallel to aline connecting the wheel centers of the two wheels from each clusterthat are in contact with the ground. In these embodiments, there arethree preferred orientations, separated by 120°, depending upon whichtwo wheels of each cluster are contacting the ground. The provision ofpowered rotation of the platform relative to the wheel clusters ensuresthat the platform will settle correctly into whichever one of the threepreferred orientations is the closest be being horizontal following astep-up or step-down operation.

Referring now to FIGS. 8A-8F, the device 10 further includes a platform30 which is hollow and configured to contain elements of a controlsystem and battery and also to keep overall device weight to a minimum.A pair of quick-release/connect latches 36 attach the platform 30 to thewheel carriers 24 (or to the link arms 12 in the case of the FIG. 1-5four-wheeled embodiment). The term “quick-release/connect latch” isunderstood to describe any mechanical latch having a configuration whichallows a user to quickly and easily actuate the latch by hand (withoutthe need to utilize any type of tool) to both engage and disengage thelatch.

FIGS. 8A to 8F show only the wheel cluster which attaches to a first endof the platform 30, with the second wheel cluster (which attaches to theopposite second end of the platform) being omitted for clarity. It willbe understood that the latch mechanism is preferably replicated on thesecond wheel cluster. The platform 30 is provided with motors 37 todrive the rotation of the platform relative to the wheel carriers 24.Although two separate motors 37 are provided on the illustrated example,the device 10 could be provided with a single motor 37 having twoindependent drive shafts. The platform 30 is provided with a matchedpair of drive shafts 35 that are driven by the respective motors 37. Inthe depicted embodiment, drive shafts 35 are internally fluted anddefine latching cavities 38.

In order to interface with these latching cavities 38, the wheelcarriers 24 are provided with a retaining guide cap 27 adapted to extendinto and latchingly engage with the latching cavity 38. Once the guidecap 27 has entered the cavity 38 it is held in place by locking wedges28. The locking wedges 28 are configured to depress when they come intocontact with the front face of the drive shaft 35 after the retainingguide cap 27 has passed into the hollow shaft, and then to springradially outward once in position within the cavity 38. The wheelcarrier 24 is also provided with an externally fluted stub axle 29 whichinterfaces with an internally fluted drive shaft 35 provided on theplatform 30.

In order to release the wheel cluster from the platform 30, the wheelcarrier 24 is provided with a release button 26 which takes the form ofa pull tab provided on a continuous internal bar linking through to theretaining guide cap 27.

FIG. 8A shows an internally sprung chamfered cavity 38. The releasebutton 26 is provided on the wheel carrier 24 between the wheels so thatthe user can access it from the outer side of the device, away from theplatform 30.

FIGS. 8B and 8C show possible alternative embodiments having therespective release buttons 26 b, 26 c and latching cavities 38 b, 38 cprovided on the wheel carrier 24 b, 24 c. In FIG. 8B the wheel carrier24 b is recessed to accommodate the cavity 38 b. In FIG. 8C the wheelcarrier 24 c is substantially planar so that the cavity 38 c protrudesfrom the wheel cluster. A sprung peg 39 protrudes from the platform 30.The disconnection between the wheel carrier 24 and the platform 30 iseffected by pulling on the button 26 to disengage it from the sprung peg39 so that the sprung peg may then be withdrawn from the cavity 38.

FIG. 8D shows the release buttons 26 d provided on the platform 30adjacent to the cavity 38 d, with the sprung peg 39 d provided on thewheel carrier 24 d. The release button 26 d is pulled to release thewheel carrier 24 d from the platform 30.

FIG. 8E shows the release button 26 e embodied as a plunger which isprovided co-axially with the platform 30. When the release button 26 eis depressed, it causes the wheel carrier 24 e to be separated from theplatform 30. In order to affect this disconnection, the platform 30 isprovided with sprung ball bearings 48.

FIG. 8F shows one possible embodiment of an electrical connector forproviding electric continuity between the wheel cluster and the platform30. Components of the connector include a slip ring 43 fixed to theplatform, a plurality of brush connections 45 disposed at the end of thedrive shaft 35, and mating connections 47 provided on the wheel carrier24. The brush connections 45 are configured to make a pressureconnection with the mating connections 47 when the latch 36 is engagedto secure the wheel carrier 24 to the platform 30. The slip ring 43 andmating connections 45, 47 enable communication of data and/or electroniccommands between the wheels 20 and the platform 30 in addition toproviding power to the motors mounted in the wheel hubs 21.

As may be seen from the above description of FIGS. 8A-8F, there isprovided a device for transporting a payload over a varied terraincomprising: a first wheel cluster comprising two or more wheels in aplanar configuration; a second wheel cluster comprising two or morewheels in a planar configuration; and a planar platform configured toaccommodate the payload; wherein each of the wheel clusters is providedwith a connector comprising an electrical connection for connection ofthe cluster to the platform such that the device can be separated intothree planar parts.

Many devices that would otherwise be suited to first/last miletransportation cannot be suitably broken down and stowed. Space is at apremium in most forms of human transportation so whether it is anovercrowded commuter train or a car or van used for private orcommercial use, the device must be capable of being flat packed in orderto be accommodated whilst the user travels.

The provision of the device as three planar parts enables assemblyand/or breakdown of the device by a user in just two steps without anytools being required.

The platform may be provided with a non-slip surface. This is especiallyimportant if the device is deployed to carry an inanimate cargo as therewill be no feedback from the user until the point of failure if thecargo slips off.

The connector may include a release button for each wheel cluster whichmay be provided on either the wheel cluster or on the platform. If therelease button is provided on the platform, one release button may beprovided for each wheel cluster. The release button may be released bypulling or pushing. The connector may further comprise a sprung peg,which may be mounted on the platform or on the wheel cluster. Theconnector may further comprise sprung ball bearings.

The electrical connection between the platform and the wheel cluster maybe provided using a slip ring, which may be mounted on the platform. Theelectrical connection may be further configured to enable data to betransferred between the wheel cluster and the platform.

The device may have a minimum range of 5 km between charges. The devicecan be charged from a 12V DC supply such as is commonly available inpassenger vehicles. This is advantageous if the device needs to be usedfor first and last miles of journey as it can be charged in transitwithin a car or van.

Alternatively, or additionally, the device can be charged from highpower 12V car/van charger with 500 W output, which takes about 20minutes. This is quicker, but not all users will have access to thischarging option so it is important that it is one of numerous optionsavailable. Alternatively, or additionally, the device can be chargedfrom AC domestic socket which takes about 20 minutes making it a quickercharging option than the 12V supply within a car.

The device is preferably sufficiently light for the user to lift is onehanded. For example, it may have a weight in the region of 10-15 kg.

FIG. 9 is a schematic illustration of a control system 40. The controlsystem 40 is preferably enclosed within the platform 30, as shownschematically in FIG. 8F. The control system 40 includes inputs (for thepurposes described elsewhere in this document, as is understood bypersons of skill in the pertinent art) from one or more sensors 42 whichmay include accelerometers, step detection sensors, gyroscopic sensors,weight/strain transducers and collision avoidance sensors (optical,radio frequency, laser, sonic, ultrasonic, etc.). The control system 40provides instructions to the hub-mounted motors within each of the hubs,via the wheel carriers 24.

The control system 40 may also be provided with a wireless/RFcommunications link 44 (Wireless Local Area Network or WiFi®, forexample). This enables tethering of the device to another device, suchas the user's mobile phone. The device may be configured to transportloads unassisted in tethered or autonomous modes. In this context,tethered refers to a digital connection via WiFi® or other similarWireless Local Area Network or BlueTooth®. Via the digital connection,the device is tethered to a second device, which could be a user's smartphone or another device as set out above. The device accelerates ordecelerates in order to remain within a predetermined range of thedevice to which it is tethered. So, if the device is tethered to theuser's smartphone and the user, carrying their smartphone, starts towalk in a first direction, the device will automatically follow theuser's smartphone, maintaining a predetermined distance from the user.In this context, autonomous refers to the use of pre-programmedinstructions including following a series of instructions or aninstruction to follow a map. Typically, when operating in an autonomousmode, the destination is known, whereas the destination may be unknownwhen operating in a tethered mode.

FIG. 10 shows schematically the aspects of the control system 40 as theywould appear to a user. After it is switched/powered on (block 100), thedevice 10 can be used in a variety of different modes, including drivemode, follow mode, autonomous mode and assisted stair walk mode. Thefirst action of the user is to select the appropriate mode for theintended usage [block 110]. As in the example of FIG. 10, if drive modeis selected [block 120], then the control system interrogates the systemsensors to identify whether two co-axial wheel pairs are in contact withthe ground [block 130]. Provided that this condition is satisfied, thenthe control system instructs the motor in the platform to rotate theplatform relative to the wheels so that the device is configured withthe platform horizontal and ready to receive a load [block 140]. Thecontrol system then senses the presence of the payload [block 150].Provided a payload is present, the control system then proceeds toperform various pre-launch checks including: whether the emergency stopbutton pressed [block 160]; and whether the weight distribution of thepayload is sufficiently even to allow safe operations [block 170. Thedevice is then ready to move forward in drive mode, in which thecontroller steers and accelerates in response to operator/rider inputs,aiming to equalize pressure on pressure pads (load cells) disposed on oradjacent to the top surface of the platform [block 180].

If, whilst driving, the control system detects, via an accelerometer orother suitable sensor, a sudden deceleration [block 190], then normaldrive mode is interrupted and curb climbing mode is initiated [blocks200, 210]. In this context, a sudden deceleration may be defined aseither a deceleration exceeding a predetermined threshold value and/orat least one wheel of the forwards wheel pair experiences a sudden braketorque in excess of a predetermined threshold. Once curb climbing modeis initiates, the control system applies a reverse thrust to the motordriving rotation of the platform and also to the forwards co-axial pairof wheels in contact with the ground [block 220]. This createssufficient torque to start the platform rotating back relative to thewheels. The control system also ensures that the hub motors in therearward set of wheels are stopped so that the rear co-axial pair ofwheels is no longer powered to rotate.

The control system then guides the device through a curb climbingoperation. The system detects whether the rearward pair of wheels haslost contact with the ground. The system also detects whether theplatform has reached 70° rotation relative to the wheel clusters [block230].

Just prior to the third pair of wheels, i.e. those that were not activeduring the immediately preceding drive mode phase, touching the ground,forward rotation is applied to these wheels [block 240]. Forwards thrustis also applied to the first co-axial wheel pair in order to aid thisco-axial wheel pair driving up the curb.

The system senses the completion of the curb climbing operation bydetecting contact between the third co-axial pair of wheels and theground [block 250]. As an ancillary check, the system also detects thedegree of rotation of the platform relative to the wheel clusters.Provided that this rotation exceeds 110°, the device is deemed to havecompleted the curb climbing operation [block 260]. Once the curbclimbing operation is complete the control system automatically switchesback to normal drive mode [block 270]. The device 10 remains in normaldrive mode until the user actively selects a different mode or until afurther sudden deceleration is detected tripping the system into curbclimbing mode again or until the sensor identifies that the device 10 isapproaching a step down requiring the device to move into a stepdescending mode.

FIGS. 11A, B and C show the three-wheel cluster vehicle step climbing.When the device hits a curb, as shown in FIG. 11A, the forward motion ofthe device is resisted by an equal and opposite force exerted by thecurb on the front wheels (20A) that touch the curb. The payload 66 isthrust forwards relative to the, now stationary, device 10, by its ownkinetic energy. The device is configured such that the force of the curbon the wheel 20A acts below the rotation axis of the platform 30. Thekinetic energy of the payload, transferred via friction between shoesand platform, initiates a forward rotation motion (clockwise as viewedin FIGS. 11A-11C) of the wheel carrier 24 about the front wheel axis(20A). Because the platform 30 is configured to rotate independentlyfrom the wheel carrier 24 about its own axis, then the platform rotatesbackwards (counterclockwise) relative to the wheel carrier to permit thedevice to continue to move forwards past the obstruction of the curb andto transfer the weight of the payload onto the co-axial wheel pair 20Bthat has been rotated and placed on top of the curb (FIG. 11C).

The powered rearward rotation of the platform 30 assists the forwardsrotation of the wheel cluster to bring the formerly redundant wheels 20Bforwards onto the curb. The platform 30 rises and falls slightly duringthe rotation of the wheel cluster. This means the rotation energybetween platform and wheel clusters must be sufficient to lift thepayload during the rise portion of the motion. Part is kinetic energyand part is the exactly timed reverse rotation of the platform axlemotor 37 (shown in FIGS. 8A-8F).

As illustrated in FIG. 11A, the rotation axis of the payload-carryingplatform 30 is higher than the wheel axis A₁ that makes contact with thecurb/step by a distance indicated as D. The resulting force vectoroffset of the opposite directed forces creates torque around the axle ofwheel 20A, initiating lift of the platform 30, resulting in rotation ofthe device 10. This forward rotation of the device 10 is assisted bytimed reverse thrust on the front wheel 20A only and controlled torqueapplied to axis of the platform 30. Once the forward-moving wheel 20Bcontacts upper step as shown in FIG. 11C, forward drive torque isapplied to both wheels 20A and 20B to pull lower wheel 20A up onto theupper step, again assisted by controlled torque applied to axis of theplatform 30 via motor(s) 37.

If the device 10 has gyroscopic control, the user achieves theillustrated sequence by firstly slowing the device by leaning back, asillustrated in FIG. 11A, where the user's heel is lower than the toe,indicating that the user is leaning back in order to slow the device 10.When the front wheel 20A hits the curb, the momentum initiates rotationof the device 10 around the front wheel 20A. Controlled torque throughwheels 20A and 20B and the platform 30 permits the climbing motion. Oncethe upper level has been achieved, the user can accelerate again byleaning forwards.

In this context, the gyroscopic control would encompass a gyroscopicsensor and a weight/strain transducer. The gyroscopic sensor isconfigured to sense the actual motion of the device. The weight/straintransducer senses user input. Together they create a feedback loopcomparing actual motion to desired user motion.

It will be understood that the same process will occur in the secondcluster of three wheels provided on the other side of the device, butthese are not shown in the interests of clarity.

FIG. 12 shows three usage modes. Each of these modes can be deployedsequentially without any alteration to the device. In FIG. 12A a humanuser is conveyed. In FIG. 12B the device 10 supports a load and hasWiFi® connectivity enabling the device 10 to be tethered to the user'ssmart phone 300. The device 10 carries a payload 66 and accelerates,decelerates and steers in order to remain within an acceptable range ofthe user at all times.

In FIG. 12C the user guides the device manually using an extendablelever 50 that is otherwise retracted into the platform 30. Lever 50serves as a torque balance lever to enable improved semi-autonomoustransportation. The lever 50 may be retractable/extendable. The lever 50allows an operator to assist the device, without bearing any of theweight of the payload. For example, climbing a curb from a stationarycondition, the payload has no kinetic energy to carry it forward. So, ifthe platform rearward rotation started, then the platform would simplytip rearwards and the payload would fall off the back of the device.With the provision of the lever 50, the operator holds the lever steadyto ensure that the wheel clusters turn forward and the device starts toclimb the stairs. The lever may be configured to enable the user toprovide a counterbalance to avoid the toppling of an inanimate payload.Without the provision of a lever, an inanimate payload could topple fromthe device during a step climbing operation. The lever enables the userto counter the forces applied by a motor within the platform whichpowers the rotation of the platform relative to the first and secondwheel clusters.

FIG. 13 shows the device 10 in stair climbing mode. The powered rotationof the two of each trio of co-planar wheels in contact with the steps atany one time enables the sequence required to lift the device up asingle curb to be repeated in order to enable the device to climbstairs.

The user (not shown) may assist the action of the device 10 by holdingan extendable lever 50 which acts as a physical torque reaction lever.

FIGS. 14A and 14B shows two examples of ways in which a transportationdevice according to the present invention may be carried in a passengervehicle after the wheel clusters are separated from the platform toallow compact carriage. In FIG. 14A, a low-floor van 400 is shown witheach wheel cluster 24 located behind a rear wheel arch 402, one at eachside of the vehicle, and the platform 30 located on top of one of thewheel arches. In FIG. 14B, which is a schematic of a car 500 with awheel well 502, each of the wheel carriers 24 and the platform 30 fit inthe well under the load floor. This carriage option takes full advantageof the fact that all three component parts 30, 24 are generally planarand relatively thin, and therefore may be positioned generally parallelwith one another for storage/carriage in a very compact fashion.

The device may have a top speed which is limited in order to becompliant with any local or state laws which regulate operation of powerboards and the like. See, for example, California AB604-2016 which setsa speed limit of 25 kph. This focuses on the utility of the device:there would be no merit in producing a technically brilliant device thatcould not be used as a result of incompatibility with local regulations.This device has been developed with relevant legislation in mind.

The device may further comprise a receptacle for holding inanimatepayloads, which receptacle may be a flip-box storage device which isconfigured to be folded flat when not in use. Such a storage device canbe deployed to hold multiple unconnected items, for example groceryshopping.

It will further be appreciated by those skilled in the art that althoughthe invention has been described by way of example with reference toseveral embodiments it is not limited to the disclosed embodiments andthat alternative embodiments could be constructed without departing fromthe scope of the invention as defined in the appended claims.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A device comprising: a platform for carrying apayload; first and second wheel clusters mounted to the platform atrespective opposite first and second ends thereof, each clustercomprising an arm attached to the platform for rotating movementrelative thereto about an axis and for translating movement relativethereto between a first position with the axis adjacent a first end ofthe arm and a second position with the axis adjacent a second end of thearm, and a first and a second wheel rotatably mounted to respectivefirst and second ends of the arm; a plurality of motors powering therotation and translation of the wheel clusters relative to the platformand the rotation of the wheels relative to the arms; and a controllercommanding the plurality of motors to enable stable rolling movement ofthe device over a surface with only one wheel of each cluster in contactwith the surface.
 2. The device according to claim 1, wherein an uppersurface of the platform defines a payload-carrying plane, and the firstand second wheel clusters define respective planes that are mutuallyparallel and orthogonal to the payload-carrying plane.
 3. The deviceaccording to claim 1, wherein the controller commands rotation andtranslation of the clusters in a manner to maintain the platform in asubstantially horizontal orientation.
 4. The device according to claim3, wherein the controller commands at least one of the plurality ofmotors in a manner to create angular rotation of the wheel clusters withrespect to the platform to allow the device to negotiate a step.
 5. Thedevice according to claim 1, further comprising at least one sensordetecting an approaching step and providing an input to the controller.6. The device according to claim 5, wherein the at least one sensorcomprises an optical sensor.
 7. The device according to claim 1, furthercomprising at least one sensor detecting a leaning motion of a userstanding on the platform and providing an input corresponding to theleaning motion to the controller.